Roulette systems are as old as roulette itself. Gamblers have tried to overcome the house edge by betting in a certain way. This relies on ‘gamblers fallacy’ where people believe that events must change to balance out the outcomes. For example, after 10 reds in a row, there must be few blacks due. This is false.
The law of large numbers says that “the average of the results obtained from a large number of trials should be close to the expected value, and will tend to become closer as more trials are performed.” The expected value of reds and black, ignoring the green, is 50% red and 50% black. The law of large numbers says as you spin more, the real values should tend to this. So if you have 55 reds and 45 blacks, you’d expect some more blacks to make the number closer to the expected values. This is not right though. The percentage will get closer to 50% but the actual number will diverge. Imagine after a million spins, you’d be really surprised if there were exactly 500,000 blacks and 500,000 reds and also if the percentages weren’t 50% red and 50% black to so many decimal places.
There are two main ways that people try to beat roulette. The first and easiest is using an mathematical betting system. The simplest and most popular is the Martingale system. Basically, you double up after each bet. All these systems are doomed to failure in the long run. Imagine if you played Russian Roulette for £1 million and won. You’d walk away a winner but was it a good idea? If you kept doing it, you’d surely blow your brains out at some point but if you did it once and walked away then maybe it is good. Just because on average its a bad idea, you might be lucky.
The other ways rely on mechanical methods on real wheels. Unlike the mathematical betting systems, these can actually work. Its not easy though and most people haven’t got the patience or nerve to use these. Also, casinos monitor their roulette wheels a lot better than in the past so some methods no longer work. See the section on physical methods to beat roulette.
If you are going to try a mathematical system, use a system tester to see the behaviour of it. Doing systems in the short run can net some profit and odd wise is no different to what a recreational roulette would play. Its all down to luck and how you manage your bank roll. Certain systems can run down the bank really quick if they are going wrong.
This is especially true of the Martingale. Read more about it here.